Di-tert.butoxydiacetoxysilane is useful especially as a cross-linking agent for the preparation of compositions which have a long shelf life under exclusion of moisture and are curable at room temperature on contact with moisture to form elastomers. Such compositions are obtained by admixing diorganopolysiloxanes containing condensable terminal groups with crosslinking silicon compounds.
U.S. Pat. No. 2,566,957 discloses that di-tert.butoxydiacetoxysilane may be prepared by reacting di-tert.butoxydichlorosilane with acetic acid in the presence of suitable acid acceptors and solvents. This process has the disadvantage that, depending upon the acid acceptor which is employed, it produces as by-products very finely divided amine hydrochlorides which are difficult to filter off or wash out. The yields of target product which can be achieved with this procedure are about 76% of theory and require the use of di-tert.butoxy-dichlorosilanes a starting material, which is accessible only by a complex process
Zhurnal obscej Chimii 27 (1957), pp. 921 to 926, discloses that alkoxyacetoxysilanes can be prepared by reacting alcohols with triacetoxysilane. In this publication it is stated that tertiary alcohols react with tetraacetoxysilane only with difficulty. If tert.butanol is used as the alcohol reactant, the reaction mixture must be warmed to temperatures of 100.degree. to 140.degree. C. in order to obtain tert.butoxyacetoxysilanes. For instance, to prepare di-tert.butoxydiacetoxysilane it was necessary to heat a mixture of tetraacetoxysilane and tert.butanol in a molar ratio of 1:2 at up to 100.degree. C. for 4 hours. Even then, the target product yield obtained by distillation of the reaction mixture was only 48% of theory.